He earned a B.Sc. and M.Sc. from University College Dublin, in his native Ireland, and then a PhD from Cornell University. He's Professor of Mathematics at Spelman College, in Atlanta, Georgia, where he's been teaching since 1988. He's currently on research leave in the DC area.

His mathematical interests are broad, and he is a recipient of the Mathematical Association of America's Allendoerfer Award for excellence in expository writing. He’s been publishing original mathematical card trick principles bi-monthly at MAA.org since 2004, and other puzzles of his have appeared in the New York Times. He also blogs as "Maths Colm" at Aperiodical and tweets as @CardColm.

He was fortunate to know Martin Gardner for the last decade of his life and is very involved in the Gardner Centennial celebrations currently unveiling.

Entries by Colm Mulcahy

"Pick up anything Martin Gardner wrote," advises mathematician, magician and MacArthur award winner Persi Diaconis. "You'll smile and learn something." This is very true, but with over 100 books to choose from, by Gardner's own estimation, where should one start?

Mathematics is all about numbers and number crunching, right? Actually, no, only part of it is. (In general, number crunching is more accurately identified with the domains of business, accountancy or engineering.)

Mathematics is more about curiosity, logic, patterns and beauty, and also has its share of delicious surprise, wonder,...

What do L. Ron Hubbard, H.G. Wells, G.K. Chesterton, Lord Dunsany, Alice in Wonderland, M.C. Escher, John H. Conway, Roger Penrose and Oprah Winfrey have in common? The same thing as Isaac Asimov, Vladimir Nabokov, and Salvador Dali. And the vase illusion shown, which was designed...

It was a beautiful May morning, and McCaw Hall in the Arrillaga Alumni Center at Stanford University was jam packed and buzzing with excitement. About 250 youngsters aged 7 to 17 had come in search of challenges and thrills, and they weren't disappointed by the festive atmosphere and friendly vibe.

It's that time of the year again. Final exams in colleges and universities are getting close, and one of the most popular questions students are asking their instructors is, "What do I have to do to get an A in this class?" (In other cases it may be, "What do...

In recent years many people have had fun attributing Bacon numbers to actors, reflecting how far removed from working with Kevin Bacon they are. Edward Asner has Bacon number 1 as he made a movie with Bacon, and Elvis Presley had Bacon number 2 (having been in an...

In my last post, I discussed the less-obvious role of mathematics in answering simple questions about biking. What about the role of biking (or hiking) in answering difficult questions about mathematics?

Aodh and Bea each biked half of a 180-kilometer fundraiser race, in that order, as a relay team. His average speed was 36 kilometers per hour, and hers was 20 kilometers per hour. What was their average speed overall?

It's not that common to become a revered national figure for over four decades in a field in which you had no formal training, having not started till you were essentially middle-aged. And then to influence a generation (or two) of enthusiasts to the extent that many ended up pursuing...